Quick-setting printing ink and process of making same



Patented June 13, 1939 UNITED STATES QUICK-SETTING PRINTING INK ANDPROG- E58 OF MAKING SAME Carleton Ellis, Montclair, N. 1.,

assiznor to Ellis laboratories, Inc., a corporation of New Jer- NoDrawing. Application April, 1938,

Serial No. 201,809

9 Claims. 250-42) This invention relates to printing inks andparticularly to typographical inks of the rapidor quick-drying type. Italso involves the preparation of printing inks which at room temperatureare fluent masses exhibiting thixotroplc proper- Printing inks oi therapidor quick-drying type may be differentiated from the usual varietyof inks by the solvent or thinning agent employed. In the formercompositions the liquid ingredient, for the most part, is one whichevaporates readily when the ink film is subjected for a short period oftime to elevated temperatures and thus efl'ects hardening or drying. Inthe ordinary type 01' 5\ printing ink the liquid vehicle is mainly anoil of the drying-oil type, and hardening or drying is the result ofatmospheric oxidation of the oleaginous material. In the latter instanceconsiderable time may elapse before complete hardening or setting of theink film is accomplished, and during which it is in a soft, more or lesspliable state. During this drying period smudging or smearing oi the inkfilm may occur ii the printed surface is subjected to undue handling orif it should come in contact with another object or surface.

Inks made according to my invention are of the quick-drying type andcomprise not only a liquid vehicle or thinning agent which evaporatesrapidly at elevated temperatures but also a heatreactive resin to serveas a binding agent. In this manner I secure an ink composition whichsets or dries not only because of rapid elimination of the liquidingredient but also due to hardening of the binding agent on theapplication of heat. Thus, when paper, on which printing is made with anink prepared according to my invention, is subjected momentarily to heatand then afterwards quickly cooled, the ink films are hardened or set,and there is little or no danger of smudging or smearing during anysubsequent handling operations.

Another distinguishing feature of my ink compositions is that theyexhibit thixotropic properties. That is, when allowed to stand, theirviscosity increases, and they become substantially non-fluid or evensolid. However, when stirred or otherwise disturbed for a short time,without the application oi heat, they resume their fluentcharacteristics and are readily flowable.

One method of preparing inks suitable for my purpose comprises reactingtwo ,or more substances, in the presence of a liquid solve'nt, whereby asolution of the resinous body is obtained. The solution is thenconcentrated to a syrup, preferably by evaporation under reducedpressure, so that the temperature may be kept as low as possible. As anillustration of this procedure urea is treated with aqueous formaldehydeand the resulting solution evaporated, under reduced pressure, until aliquid product of syrupy consistency is secured. During the evaporationstep an inert gas, e. g., nitrogen, may be passed through the liquid,thus aiding in more rapidly concentrating the mass to desired degree ofconsistency. The product, on cooling, appeared as a soft, semi solidmass. The thixotropic properties of this composition are readily shownby vigorously stirring the mass whereupon it becomes fluent or ilowable,but again slowly becomes a more or less solid mass when allowed to standundisturbed.

After concentrating the solution of resinous material to a syrup andduring cooling of the latter to room temperature, some clouding of theliquid mass or partial precipitation oi the resin occurs. This is notdetrimental to my purpose provided such insoluble material remainsdispersed throughout the liquid and does not settle out or coagulate.

With the thixotropic mass is incorporated the pigment and, if desired,extending agents, fillers, modifying agents, etc. In selection of thelatter materials it should be borne in mind that they must not possessor exhibit properties which would be detrimental or deleterious to thethixotropy shown by the resin syrup.

Another procedure comprises reacting urea and the aldehyde in thepresence of water as a solvent and then adding a miscible higher-boilingsolvent, e. g., glycol or glycerol. The resulting product is thenconcentrated to a thixotropic mass by heating under reduced pressure. Inthis manner a large proportion, if not all, 01' the water may bereplaced or substituted by the higher-boiling solvent. Pigment and, ifdesired, modifying agents are incorporated with the concentratedthixotropic mass.

In some instances I may admlx the thixotropic syrup with a resinoussyrup which does not show thixotropic properties, and the mixture servesas the source of the binding agent for my ink compositions. Examples ofresin syrups, which may be prepared in a non-thixotropic condition andare suitable for blending, are concentrated aqueous solutions of bodiesresulting from the interaction oi thiourea and formaldehyde or phenoland formaldehyde. The resin syrups, of course, should be compatible sothat they mix or blend readily and no evidence of any undesirableinteraction is obtained. It is necessary, also, that the proportion ofthixotropic syrup be sufllciently great that the resulting compositionexhibits thixotropic to a substantial extent and thus be suitable for mypurpose.

- In other cases it may be advantageous to interact (in the presence ofwater) urea and formaldehyde, using a considerable excess of the latter,

and then add thiourea to the product to react with the remainingaldehyde. In this manner a liquid homogeneous mixture of the tworesinous bodies is secured which may be concentrated to a thixotropicsyrup.

Although water will serve admirably as the liquid ingredient in manycases, I do not wish to limit my invention to the use of this fluidonly. Examples of other media which are suitable for my purpose includemonoor polyhydric alcohols, e. g., isobutanol and glycol, or esters suchas glycol monoor diacetate, or ethers, for example, diethylene glycol.

The following examples will illustrate my invention. All parts are byweight.

Example 1.Flfty parts of urea and 200 parts of an aqueous 37 per cent(by weight) solution of formaldehyde were heated, under reflux for 30minutes, on a water bath. During this operation the pH of the solutionwas maintained at about 7 by using bromothymol blue as an indicator andoccasionally adding a few drops of aqueous alkali. At the end of theheating period the liquid product was evaporated under reduced pressureand at a temperature not exceeding 70 C. until its water or othervolatile material content was approximately 24 per cent. In the thicksyrupy liquid was dissolved sufiicient glycerol dischlorohydrin (as acatalyst for hardening the resin) to give a 2 per cent solution. Fiveparts of the liquid mixture were ground with 0.5 part of carbon black.The composition so obtained was of the short ink type and possessed goodbody and tack. A thin film of it on paper dried quickly at 160 C.

This ink composition exhibite'd thixotropic properties, i. e., onstanding gradually became solid, and when the solid composition wassubjected to a mild grinding operation, it rapidly became fluid.

Example 2.Fifty parts of phenol (carbolic acid), 87.5 parts of anaqueous 37 per cent (by weight) solution of formaldehyde, and 1.4 partsof caustic soda were reacted at 70 C. for 2% hours. Afterwards theliquid mixture was neutralized with lactic acid and distilled underreduced pressure, the temperature not exceeding 60 0., until its wateror other volatile material content was approximately 18 per cent. Sixparts of this syrup and 6 parts of the syrup as prepared in Example 1were mixed and then 1 part of glycerol dichlorohydrin incorporated.Afterwards 1.5 parts of carbon black were ground into the liquidcomposition. This ink exhibited good flow, body and tack. A thin fllm ofit dried rapidly at temperatures of 140 C. and higher.

On standing the ink stifi'ened considerably but did not become solid.When the stifl'ened product was stirred, it readily became liquid andflowable again.

Example 3.As an indication of the degree of thixotropy exhibited by aurea-formaldehyde syrup, penetration measurements were made after thesyrup had been ground or stirred, after the latter had stood for severalhours, and then after regrinding or restirring the syrup. 7

The following method was used: In the plunger of a penetrometer wasinserted a needle, 3.35 mm. in diameter, having a flat circular head 7mm. in diameter. The needle and plunger weighed 52 grams. The timerequired for the needle to penetrate the syrup to a specified distancewas then determined. In all instances penetration was ascertained firstwhile the syrup was in the liquid or fluid state (rendered so bygrinding or stirring), after which the syrup was allowed to stand andassume the more viscous or even solid state. Penetration was againmeasured while the syrup was in the latter condition. This sequence ofchanges of state and determination of penetration can be repeatedseveral times if desired. (This same apparatus and procedure wereemployed in all other examples of penetration determinations describedherein. When the,weight of the plunger and needle was insumcient toefi'ect reasonably rapid movement through the sample (thixotropic resinsyrup or ink composi-- tion therefrom), additional weights were placedon the plunger. In all cases measurements were made at roomtemperature).

A syrup was prepared, as described in Example 1, using 60 grams of ureaand 225 grams of aqueous formaldehyde. This syrup contained 27 per centof material volatile at l00-105 C. Penetration measurements on theproducts were as follows:

Condition 0! syrup gg zg Weight Millimeter: Stirred 25 85 After standing2 days No penetration Restirred l 25 Grams Distance pene- Condition ofink rated Weight Miilimelers Stirred 26 After standing overnight Nopenetration Resin-red 25 20 Grams Example 5.Seven parts of theurea-resin syrup (as prepared in Example 1) were mixed with 3 parts ofthe phenolresin syrup (as prepared in Example 2). Afterwards there wereincorporated, in the order mentioned, 0.5 part of glyceroldichlorohydrin, 0.8 part of carbon black, and 0.3 part of a blue toner.The resulting ink composition was somewhat heavy-bodied but flowable.Films oi it dried very quickly at temperatures of 155 C. and higher.

This ink exhibited thixotropic properties analogous to those describedin Example 2.

Example 6.An aqueous urea-formaldehyde syrup was secured by refluxingfor twenty minutes a. mixture of 75 parts of urea and 275 parts ofaqueous 37 per cent (by weight) formaldehyde solution. During thisoperation the pH of the solution was maintained at about 7. The liquidproductwas subjected to distillation under reduced pressure (29.5 inchesof mercury), the temperature being kept at 6570 C., until the loss inweight amounted to 150 parts. During distillation a slow stream ofcarbon dioxide was bubbled through the liquid mass to aid in removingvolatile portions. The liquid mass on-cooling Distance Condition of inkpenetrated Time Weight Millimeter: After sitrrin Alter stan RestirrcdAfter standing 2 days more. Restirrcd Example 8.-Thirty-flve parts ofurea were added to 190 parts of 3'7 per cent (by weight) aqueoussolution of formaldehyde. Reaction was started by gently heating themixture under reflux, after which the source of heat was withdrawn andinteraction allowed to proceed spontaneously. With the latter apparentlyceased, as evidenced by no further boiling or formation of bubbles inthe liquid, 15 parts of thiourea were added and the mixture heated(under reflux) for 30 minutes. During these operations the pH of thesolution was maintained at about 7, as described in Example 1. Theliquid product so obtained was concentrated by evaporation, underreduced pressure and temperautre not exceeding 10 C., until its water orother volatile material content was about 17 per cent. Whileconcentration was being eflected, a stream of carbon dioxide gas waspassed through the liquid mass.

In 6 parts oi the syrup was dissolved 0.3 part of glyceroldichlorohydrin. Afterwards there were incorporated in the liquid mixture(in the order named) 0.5 part of red pigment, 0.? part of magnesiumcarbonate and 0.3 part of hydrated aluminum oxide (as extending agents).This ink composition, though possessing a heavy body, had good flow andtack, and films of it (on paper) dried in a few seconds at temperaturesof 130 C. and higher.

Example 9.To 20 parts of ethylene glycol were added 30 parts of urea andthe mixture kept at about C. until all the solid was completely wettedby the liquid. Afterwards 30 parts of paraformaldehyde were added, andthe whole mass maintained at 80 C. for about 45 minutes. Duringinteraction of urea and aldehyde the pH of the liquid was maintained atabout '1 by addition of alkali. A clear syrup was obtained which oncooling to room temperature appeared as a thixotropic mass.

Six parts of the thixotropic product were ground with 0.6 part of carbonblack. The resulting ink composition was somewhat heavybodled, butpossessed good flowing qualities. The fluid mass, on standing, slowlychanged to a solid mass. The latter was readily made fluid again bygrinding.

Example 10.--A syrup, made as described in Example 9, exhibitedthlxotropic properties as indicated by the following measurements ofpenetration.

- Distance Condition oi syrup ponetmmd Time Weight Millimeter! SecondsGrams Alter stirring 29 l. 6 52 After standing overnight 29 11.8 52Restirred 29 2 52 Example 11.-An ink composition, formulated asindicated in Example 9, gave the following data when tested with apenetrometer.

Distance Condition of ink pene- Time Weight trated Millimeter; SecondsGrams After stirring 27 14 102 Alter standing overnight. 27 350 102Restirred 27 2.5 l02 Alter standing 3 days mor 27 202 Restirl'ed 27 3410:. Alter standing 1 day more 27 235 202 27 95 l02 27 203 202 27 i5!102 Example 12.-With 5 parts of the thixotropic syrup, as prepared inExample 9, were incorporated 1.5 parts of zinc sulphide, 0.5 part ofhydrated alumina and 0.5 part ofzinc oxide. Afterwards there were workedinto the composition 1.5 parts of a 10 per cent solution of ethylcellulose in benzyl alcohol. The resulting white ink exhibited good flowand body, and thin films of it dried quickly at a temperature of 155 C.It also possessed thixotropic properties.

Example 13.-A thixotropic resin syrup was made, employing the proceduredescribed in Example 9, from 35 parts of urea, 35 parts ofparaformaldehyde and 20 parts of ethylene glycol.

Four parts of the thixotropic syrup were ground with 1.5 parts of a 10per cent solution of ethyl cellulose in benzyl alcohol, and then 0.7part of an orange-colored pigment was added. This ink compositionpossessed very good flow, and thin films oi it (on paper) dried in a fewseconds at C. It also exhibited thixotropic properties.

Example lat-Another thixotropic syrup was prepared, according to theprocedure described in Example 9, but using 35 parts of urea, 35 partsof paraformaldehyde and 25 parts of diethylene glycol. After cooling toroom temperature, 5 parts more of diethylene glycol were worked into themass.

With '1 parts of the above syrup were incorporated 0.'l part of a redpigment and 0.15 part of glycerol dichlorohydrin. The red ink thus madepossessed good flowing qualities, and thin films of it dried in a fewseconds at 145 C.

Example 15.-Penetration measurements were made using a thixotropicresinous syrup which Example 16.-A thixotropic printing ink compositionwas made by incorporating 6 parts of a red pigment and 1.3 parts ofglycerol dichlorohydrin with 61 parts of the syrup as prepared inExample 14. Penetration measurements were made over a period of severaldays with the following results. In all instances the weight was 52grams.

Condition of ink g zfigff Time lllflh'melcrs Srcondc Alter stirring 28 8Alter standing 2 days 28 i5 Restirred 28 7 After standing 1 dayadditional 2s Restirred 28 7 6 After standing 3 days more. .28 35Restirred 28 i. B After standing 1 day additional 29 57 Restirred 28 .8.2 After standing 2 days more. .38 83 Restirred U. 28 7. B

Although my invention has been illustrated with resinous bodies madefrom urea. and formaldehyde, I do not wish to limit myself to theemployment of only formaldehyde. In many instances other aldehydes, suchas acetaldehyde, benzaldehyde and the like, may serve equally well tofurnish resinous bodies which will yield syrupy compositions exhibitingthixotropic properties. Furthermore, in addition to using mixtures ofurea and thiourea in the preparation of thixotropic, syrupycompositions, I may replace either one or both of them by theirsubstituted derivatives, e. g., methyl urea.

In many of the inks, according to my inven tion, water may be the liquidvehicle or thinning agent, and as such it possesses many advantages. Forexample, it is classed as a non-flammable and inexpensive ingredient.Again, its boiling point is sufliciently low so that very hightemperatures (and possible consequent damage therefrom to the printedsurface) are not required for rapid hardening of ink films containingthis ingredient. However, the proportion of water in the ink compositionshould not be sufficiently great as to cause undue wetting or otherundesirable eilects when the ink films are applied to paper or otherappropriate surfaces. As previously mentioned, though, many liquidvehicles, such as alcohols, esters and ethers, are suitable for mypurpose.

It will be seen that the inks which fall within the scope of myinvention are those which comprise a binding agent consisting of one ormore heat-reactive synthetic resins, pigmenting material, and a liquidvehicle. By the term heatreactive I mean that the resinous body isinitially soluble in certain solvents and fusible, but that on theapplication of sufficient heat it becomes insoluble and, in manyinstances, also infusible. The liquid vehicle, which serves as thesolvent or thinning agent, should be present in the requisite proportionto render the ink composition thixtropic at room temperature, 1. e., thesaid composition becomes considerably more viscous or even solid onstanding, but is readily reconverted into a fluent or fiowable mass whensubjected to a mild stirring or grinding operation. Furthermore, theliquid vehicle should not be so volatile that the ink will dry or settoo rapidly at room temperature, but will permit ready hardening of afilm of ink when the latter is subjected to slightly elevatedtemperatures.

In addition to the above-named components there may be present alsosmall proportions of modifying agents. The latter include suchmaaterials as catalysts which quicken or accelerate hardening of theresin when heat is applied to the ink film, extending agents (such ashydrated alumina) to be employed in conjunction with pigmenting bodies,and materials which alter the flow, body or tack of the ink composition.Examples of the latter materials are cellulose ethers and esters.

My invention also involves the preparation of thixotropic compositionsto be employed in the formulating of printing inks. Such compositionscomprise the heat-reactive resinous binding agent and aliquid vehicle.They may be obtained, for example, by reacting the components, fromwhich the resin is derived, in the presence of a relatively largequantity of liquid vehicle and then concentrating the resulting solutionof resin until the proportion of liquid vehicle is sufficient to furnisha product having thixotropic properties at room temperature. Thixotropiccompositions particularly suitable for my purpose are those containingaminoplasts, or resinous bodies arising from the interaction of aminocompounds and aldehydes, illustrative of which is the reaction productfrom urea and formaldehyde. Another phase contemplates effectinginteraction of the components, from which the resin is derived, in thepresence of suilicient liquid vehicle to give a thixotropic mass withoutthe necessity of concentrating the reaction product.

Again, non-thixotropic syrups of resins may be incorporated with thethixotropic resinous compositions to yield binding agents consisting oftwo or more resinous bodies. The syrup which does not exhibitthixotropic properties should, of course, be miscible and compatiblewith the thixtropic composition, and the proportion of the former shouldnot be sufficiently great to render the mixture non-thixotropic. By theterm resin syrup or syrup of resin as used herein I mean the thick,viscous, flowable solutions obtained by the solution of the resinousmaterial in a relatively small proportion of solvent. Preferably thenon-thixotropic syrups are of extraneous origin, i. e., the resinousbodies therein represent a type distinct from that in the resinousmaterials exhibiting thixotropy. For example, a nonthixotropic syrup ofa phenol-formaldehyde resin (syrup of extraneous origin) may beincorporated with a thixotropic urea-formaldehyde composition. Othernon-thixotropic syrups of phenoplasts or resinous compositions derivedfrom phenolic bodies and aldehydes may, of course, be employed.

It should be noted also that many of the binding agents suitable for mypurpose, e. g., those derived from urea and formaldehyde, or sometimeseven from phenol and formaldehyde, are colorless or substantially so.This will be recognized as extremely advantageous, particularly in thepreparation of colored printing inks such as reds, blues, greens and thelike. The binding egent, being substantially free of any undesirabeltint, will not interfere with the coloring power of the pigmentingmaterial, thus allowing in many instances the employment of less pigmentto secure the desired degree or shade of color without any noticeabledisturbing undertone.

What I claim is:

l. A quick-drying printing ink composition comprising a binding agentconsisting of a heatcording to claim 1, in which the binding agent isderived from urea and an aldehyde.

3. A quick-drying printing ink composition, according to claim 1, inwhich the binding agent is derived from urea and formaldehyde.

4. A quick-drying printing ink composition, according to claim 1, inwhich the binding agent is derived from urea and an aldehyde and isadmixed wlth a compatible resin syrup 0! extraneous origin notexhibiting thixotropic properties, the proportion of said resin syrupbeing insumcient to destroy the thixotropic properties of said inkcomposition.

5. The process which comprises concentrating a solution oi. aheat-reactive aminoplast resin to a fluent mass having thixotropicproperties at room temperature, and incorporating pigmenting material,whereby a fluent quick-drying printing ink composition havingthixotropic propertiw at room temperature is obtained. 6. The process,according to claim 5 in which the heat-reactive aminoplast resin isderived from urea and an aldehyde.

I 'l. The process which comprises concentrating a solution of aheat-reactive resinous product derived from urea and an aldehyde to afluent mass possessing thixotropic properties at room temperature,admixing said fluent mass with a compatible resin syrup oi extraneousorigin not exhibiting thixctropic properties at room temperature, theproportion oi said resin syrup being insuflicient to destroy thethixotropic properties of said fluent mass, and incorporating pigmentingmaterial, whereby a. fluent quick-drying printin ink composition havingthixotropic properties at room temperature is obtained.

8. ,Theprocess which comprises reacting urea and an aldehyde to give aheat-reactive resinous product and simultaneously incorporating a liquidvehicle, the proportion oi said liquid vehicle being suiiicient torender said product a fluent mass having thixotropic properties at roomtemperature, and incorporating pigment material. whereby a fluentquick-drying printing ink composition having thixotropic properties atroom temperature is obtained.

9. The process which comprises reacting urea and an aldehyde to give aheat-reactive resinous product and simultaneously incorporating a liquidvehicle, the proportion oi said liquid vehicle being suflioient torender said product a fluent mass having thixotropic properties at roomtemperature, admixing said fluent mass with a compatible resin syrup oiextraneous origin not exhibiting thixotropic properties at roomtemperature, the proportion oi said resinoussyrup being insuiiicient todestroy the thixotropic properties oi said fluent mass, andincorporating pigmenting material. whereby a fluent quick-dryingprinting ink having thixotropic properties at room temperature isobtained;

CARLE'ION ELLIS.

CERTIFI a m or CORRECTION.

Patent No 2,162, 1.

June 13, 1959.

csnmron sLLIs.

. It is hereby certified that oi theabove numbered patent re and column,line 57, Example 1;,

of the phenol-re sin syrup (as I pre- 1.; parts or; and that the saidLet correctiontherein that the some may conform to the the woe. sealed(as air error appear iring correction as follows: for the words andsylla read with jpsrts' of this 19th day or'septernber, a e. 19 9.

Henry van .iredale, Acting Qmnmissioner of Patents.

cording to claim 1, in which the binding agent is derived from urea andan aldehyde.

3. A quick-drying printing ink composition, according to claim 1, inwhich the binding agent is derived from urea and formaldehyde.

4. A quick-drying printing ink composition, according to claim 1, inwhich the binding agent is derived from urea and an aldehyde and isadmixed wlth a compatible resin syrup 0! extraneous origin notexhibiting thixotropic properties, the proportion of said resin syrupbeing insumcient to destroy the thixotropic properties of said inkcomposition.

5. The process which comprises concentrating a solution oi. aheat-reactive aminoplast resin to a fluent mass having thixotropicproperties at room temperature, and incorporating pigmenting material,whereby a fluent quick-drying printing ink composition havingthixotropic propertiw at room temperature is obtained. 6. The process,according to claim 5 in which the heat-reactive aminoplast resin isderived from urea and an aldehyde.

I 'l. The process which comprises concentrating a solution of aheat-reactive resinous product derived from urea and an aldehyde to afluent mass possessing thixotropic properties at room temperature,admixing said fluent mass with a compatible resin syrup oi extraneousorigin not exhibiting thixctropic properties at room temperature, theproportion oi said resin syrup being insuflicient to destroy thethixotropic properties of said fluent mass, and incorporating pigmentingmaterial, whereby a. fluent quick-drying printin ink composition havingthixotropic properties at room temperature is obtained.

8. ,Theprocess which comprises reacting urea and an aldehyde to give aheat-reactive resinous product and simultaneously incorporating a liquidvehicle, the proportion oi said liquid vehicle being suiiicient torender said product a fluent mass having thixotropic properties at roomtemperature, and incorporating pigment material. whereby a fluentquick-drying printing ink composition having thixotropic properties atroom temperature is obtained.

9. The process which comprises reacting urea and an aldehyde to give aheat-reactive resinous product and simultaneously incorporating a liquidvehicle, the proportion oi said liquid vehicle being suflioient torender said product a fluent mass having thixotropic properties at roomtemperature, admixing said fluent mass with a compatible resin syrup oiextraneous origin not exhibiting thixotropic properties at roomtemperature, the proportion oi said resinoussyrup being insuiiicient todestroy the thixotropic properties oi said fluent mass, andincorporating pigmenting material. whereby a fluent quick-dryingprinting ink having thixotropic properties at room temperature isobtained;

CARLE'ION ELLIS.

CERTIFI a m or CORRECTION.

Patent No 2,162, 1.

June 13, 1959.

csnmron sLLIs.

. It is hereby certified that oi theabove numbered patent re and column,line 57, Example 1;,

of the phenol-re sin syrup (as I pre- 1.; parts or; and that the saidLet correctiontherein that the some may conform to the the woe. sealed(as air error appear iring correction as follows: for the words andsylla read with jpsrts' of this 19th day or'septernber, a e. 19 9.

Henry van .iredale, Acting Qmnmissioner of Patents.

